Edmonds astronomer discovers ‘Earth-like’ planet

Agol, the University of Washington astronomer whose discovery of a planet was announced last year, is now credited with finding another.

The planet, Kepler-62f, is one of five planets in the same planetary system. It’s being called the most “Earth-like” planet found outside the solar system — way outside the solar system.

The star it revolves around is 1,200 light-years away. Even at that distance, “it’s in the neighborhood, as far as the galaxy is concerned,” Agol said.

Kepler-62f is about 1.4 times the size of Earth and circles its star in 267.3 days, almost 100 days shorter than an Earth year.

This planetary finding is more exciting than last year’s, Agol said. Although it’s similar in size, it has a cooler temperature. It’s cool enough to have Earth-like liquid water, rather than a steamy atmosphere or no atmosphere at all, he said.

“It has properties more similar to Earth’s than others we’ve found,” Agol said.

The discovery of the planets was published Thursday in the online edition of the journal Science.

Agol, 42, who lives in Edmonds, is an astrophysicist and associate professor of astronomy who says his true love is physics and math. “I didn’t own a telescope until I got my Ph.D,” he said.

The recent discovery of planets with rocky surfaces and temperatures likely for liquid water “brings us a bit closer to finding a place like home,” NASA administrator John Grunsfeld said in a statement. “It is only a matter of time before we know if the galaxy is home to a multitude of planets like Earth, or if we are a rarity.”

The detective work to find planets outside the solar system is being conducted by the Kepler telescope, launched in 2009 by NASA. Its mission is to detect Earth-sized planets in orbits around stars similar to the sun.

In August, scientists found three planets circling a star. And then came the moment when Agol thought he had spotted another.

“I identified this as a candidate, did some modeling … and confirmed this was actually a planet,” Agol said.

“It was pretty convincing right away,” he said. “It was just a coincidence that they had missed it.”

Agol has been working on the Kepler project about two years, using new software and mathematic calculations to try to detect new planets that may have been missed in other searches.

The Kepler space telescope measures the brightness of more than 150,000 stars. But even with so much to keep watch on, it can only cover 1/400th of the entire sky, Agol said.

The work is done by a digital camera on the spacecraft, which takes a picture of one portion of the sky every six seconds. Those images are added together with pictures taken over a half hour. They’re sent to Earth, processed by NASA, and then made available to scientists.

The star the new planet is revolving around is faint compared to other nearby stars, but still can be spotted by an amateur astronomer using a telescope, Agol said.

Although the Kepler mission has discovered 122 planets so far, the discovery of Kepler-62f, the planet with such an unassuming name, was special.

“This turned out to be one of the most interesting ones to date,” he said.